In recent years, with the widespread use of mobile devices such as laptop computers, smart phones, cameras and other portable electronics, the need for high energy-density batteries becomes increasingly important.
In the present technology, a battery comprises a positive electrode plate, a negative electrode plate, electrolyte, and two membrane separators for preventing electronic contact of the electrodes. In the machining process, it is easy to form burrs on the electrode plates. It is probable that the burrs penetrate the membrane separator when the battery elements are wrapped and stacked and this gives rise to an internal short circuit. The burrs generated on the edge of the battery case may also come off to cause an external short circuit between the battery case and the lid (sealing plate), thereby causing a voltage drop. Therefore, the electrode burrs greatly affect the quality and performance of batteries.
To date, several methods have been proposed to deburr the electrodes using chemical or mechanical methods. Wang et al. described in their patent a method for removing burrs of electrode plates by passing the electrode plates through rotating rolls on a conveyer belt to flatten the burrs. This technique essentially applies suitable pressure on the edge of electrode plates to virtually eliminate burrs. However, this mechanical method only blunts the burrs without completely eliminating them, so it has many limits in removing the burrs resulted from the cutting of battery electrode plates.
Guo et al. described another technique which employs a chemical reaction of alkaline substance with aluminum to remove the burrs of the negative electrode plate. However, this chemical method has a serious corrosion effect as part of the surface of the electrode is etched. The small burrs cannot be completely eliminated. Also, when coiled material is processed using this method, undesirable contamination may take place due to capillary action, degrading the quality of batteries.
ICP dry etching is a method in which material is etched by ion bombardment and reaction with reactive gas in the plasma. This method has excellent anisotropy, convenient operation, low cost and high etching rate.